Production tool to make abrasive particles with grooves

Abstract

Abrasive particles comprising shaped abrasive particles each having a sidewall, each of the shaped abrasive particles comprising alpha alumina and having a first face and a second face separated by a sidewall and having a maximum thickness, T; and the shaped abrasive particles further comprising a plurality of grooves on the second face.

What is claimed is: 
     
       1. Abrasive particles comprising:
 dish-shaped abrasive particles each having a sidewall; 
 wherein each of the dish-shaped abrasive particles comprises alpha alumina and has a first face and a second face separated by a varying thickness (T); 
 wherein the sidewall forms a perimeter of the first face and a perimeter of the second face and the geometric shape of the perimeter of the first face and second face is triangular or star-shaped; 
 wherein the first face is recessed and a thickness ratio of Tc/Ti for the dish-shaped abrasive particles is between 1.25 and 4.0, wherein Tc is the thickness at a corner of the sidewall and Ti is the smallest thickness of an interior of the first face; 
 wherein, in order to calculate the thickness ratio, 
 fifteen randomly selected dish-shaped abrasive particles are screened, the thickness of each corner of each dish-shaped abrasive particle is measured and then all of the thicknesses of the corners are averaged to determine an average Tc; 
 the smallest thickness Ti of the interior of the first face of each of the fifteen randomly selected dish-shaped abrasive particles is measured and the fifteen results are averaged to determine an average Ti; and 
 the thickness ratio is determined by dividing the average Tc by the average Ti. 
 
     
     
       2. The abrasive particles of  claim 1 , wherein the second face is substantially planar. 
     
     
       3. The abrasive particles of  claim 1 , wherein the first face comprises a substantially planar center portion and a plurality of raised corners. 
     
     
       4. The abrasive particles of  claim 1 , wherein the first face is concave. 
     
     
       5. The abrasive particles of  claim 1 , comprising a draft angle (α) between the second face and the sidewall, wherein the draft angle (α) is between about 95 degrees and about 130 degrees. 
     
     
       6. The abrasive particles of  claim 5 , wherein the draft angle (α) is between about 95 degrees and about 110 degrees. 
     
     
       7. The abrasive particles of  claim 1 , wherein the perimeter comprises a triangular shape. 
     
     
       8. The abrasive particles of  claim 7 , wherein the triangular shape comprises an equilateral triangle. 
     
     
       9. The abrasive particles of  claim 1 , comprising a radius of a sphere curve-fitted to the first face by image analysis, wherein the radius is between about 1 mm and about 25 mm. 
     
     
       10. The abrasive particles of  claim 9 , wherein the radius of the sphere curve-fitted to the first face by image analysis is between about 1 mm and about 14 mm. 
     
     
       11. An abrasive article produced from the abrasive particles of  claim 1 . 
     
     
       12. A plurality of dish-shaped abrasive particles made from a material comprising alpha alumina, the dish-shaped abrasive particles comprising a body having a first face, a second face spaced from the first surface by a varying thickness, and a sidewall, wherein the sidewall of the dish-shaped abrasive particles forms a perimeter of the first face and the second face, wherein the perimeter of first face and the perimeter of the second face are of a triangular or star shape, and wherein the first face is recessed such that corners of the dish-shaped abrasive particles are elevated higher than an interior of the first face, and wherein the first face by being recessed results in an acute angle (λ) between the sidewall and the first face and a thickness (Tc) at the corners of the dish-shaped abrasive particles is greater than a thickness (Ti) in an interior of the first face;
 wherein a thickness ratio of Tc/Ti for the dish-shaped abrasive particles is between 1.25 and 4.0, wherein, in order to calculate the thickness ratio,
 fifteen randomly selected dish-shaped abrasive particles are screened, the thickness of each corner of each dish-shaped abrasive particle is measured and then all of the thicknesses of the corners are averaged to determine an average Tc; 
 the smallest thickness Ti of the interior of the first face of each of the fifteen randomly selected dish-shaped abrasive particles is measured and the fifteen results are averaged to determine an average Ti; and 
 the thickness ratio is determined by dividing the average Tc by the average Ti. 
 
 
     
     
       13. The dish-shaped abrasive particles of  claim 12 , wherein the sidewall is a sloping sidewall having a draft angle (α) greater than 90 degrees. 
     
     
       14. The dish-shaped abrasive particles of  claim 12 , wherein the perimeter of the first face and the second face differ in size with one face being larger than the other face. 
     
     
       15. The dish-shaped abrasive particles of  claim 12 , wherein the triangular shape is one of an equilateral triangular shape or an isosceles triangular shape. 
     
     
       16. The dish-shaped abrasive particles of  claim 12 , wherein the first face is recessed and the second surface is substantially planar so that the thickness (Ti) of an interior of the first face is thinner than the thickness of the dish-shaped abrasive particle along the perimeter. 
     
     
       17. The dish-shaped abrasive particles of  claim 16 , wherein the recessed face has a substantially flat center portion and upturned corners, or wherein the recessed face is substantially concave. 
     
     
       18. The dish-shaped abrasive particles of  claim 12  having a thickness ratio between 1.55 to 2.32. 
     
     
       19. The dish-shaped abrasive particles of  claim 12 , wherein a sidewall thickness is greater at the corners of the dish-shaped abrasive particles and thinner at midpoints along each edge. 
     
     
       20. The dish-shaped abrasive particles of  claim 12 , wherein the dish-shaped abrasive particles are made from a dispersion of aluminum oxide monohydrate that is gelled, molded to shape, dried to retain the shape, calcined, and sintered. 
     
     
       21. An abrasive article comprising a plurality of the dish-shaped abrasive particles according to  claim 12 . 
     
     
       22. The abrasive article of  claim 21 , wherein the dish-shaped abrasive particles are applied in a backing in an open coat abrasive layer, wherein there is less than 100% coverage of a make coat with the abrasive particles, thereby leaving open areas and a visible resin layer between the particles. 
     
     
       23. The abrasive article of  claim 22 , wherein the percent open area in the abrasive layer is between 10% and 90%. 
     
     
       24. The dish-shaped abrasive particles of  claim 12 , wherein the thickness ratio of Tc/Ti is between 1.30 to 4.00. 
     
     
       25. The dish-shaped abrasive particles of  claim 12 , wherein the thickness ratio of Tc/Ti is between 1.30 to 3.00. 
     
     
       26. The abrasive particles of  claim 1 , wherein the thickness ratio of Tc/Ti is between 1.30 to 4.00. 
     
     
       27. The abrasive particles of  claim 26 , wherein the thickness ratio of Tc/Ti is between 1.30 to 3.00. 
     
     
       28. The abrasive particles of  claim 27 , wherein the thickness ratio of Tc/Ti is between 1.55 to 2.32. 
     
     
       29. The abrasive particles of  claim 1 , wherein the thickness ratio of Tc/Ti is between 1.25 to 3.00. 
     
     
       30. A plurality of abrasive particles made from a material comprising alpha alumina, the abrasive particles comprising a body having a first face, a second face spaced from the first surface by a thickness, and a sidewall, wherein the sidewall of the abrasive particles forms a perimeter of the first face and the second face, wherein the perimeter of first face and the perimeter of the second face are of a triangular or star shape, wherein the abrasive particles comprise a thickness (Tc) at the corners of the abrasive particles and a thickness (Ti) in an interior of the first face;
 wherein a thickness ratio of Tc/Ti for the abrasive particles is between 1.25 and 4.0, wherein, in order to calculate the thickness ratio,
 fifteen randomly selected abrasive particles are screened, the thickness of each corner of each abrasive particle is measured and then all of the thicknesses of the corners are averaged to determine an average Tc; 
 the smallest thickness Ti of the interior of the first face of each of the fifteen randomly selected abrasive particles is measured and the fifteen results are averaged to determine an average Ti; and 
 the thickness ratio is determined by dividing the average Tc by the average Ti; 
 wherein the abrasive particles that are calculated to have the thickness ratio are dish-shaped abrasive particles having a recessed first face. 
 
 
     
     
       31. The abrasive particles of  claim 30 , wherein the first face is recessed such that corners of the dish-shaped abrasive particles are elevated higher than an interior of the first face, and wherein the first face by being recessed results in an acute angle (λ) between the sidewall and the first face. 
     
     
       32. The abrasive particles of  claim 30 , wherein the thickness ratio of Tc/Ti is between 1.25 to 3.00. 
     
     
       33. The abrasive particles of  claim 30 , wherein the thickness ratio of Tc/Ti is between 1.30 to 4.00. 
     
     
       34. The abrasive particles of  claim 30 , wherein the thickness ratio of Tc/Ti is between 1.30 to 3.00. 
     
     
       35. The abrasive particles of  claim 30 , wherein the thickness ratio of Tc/Ti is between 1.55 to 2.32.